Last updated on March 31st, 2022
Crawl space repair cost guide
Moisture seeping in from your crawl space could make your home damp and unhealthy. Find out how much crawl space repair & cleaning cost here.

When issues are spotted early, the cost to repair your crawl space is reduced compared to being noticed much later. The same goes for the crawl space cleaning cost. And sometimes, time is the only difference between requiring a crawl space clean or repair.
The common issue that occurs with crawl spaces is when moisture appears and over time it causes damage. The longer it’s left untreated the more damage that is caused, and therefore, the higher the repair and cleaning costs will be.
Moisture coming from your crawl space will ruin your flooring over time. So, if you’re seeing signs of dampness on your floor, it’s worth checking out the area under your house.
So, what’s the cost of crawl space repair and cleaning?
Crawl space repair cleaning cost
Cost provided item | Unit | Range - Low | Range - High | Average cost |
---|---|---|---|---|
Crawl space cleaning and repair cost | Per job | £1,100 | £11,000 | £6,050 |
Crawl space waterproofing cost | Per job | £1,200 | £12,000 | £6,600 |
Crawl space floor joist replacing cost | Per joist | £75 | £220 | £150 |
Crawl space encapsulating cost | Per job | £1,200 | £12,000 | £6,600 |
Dehumidifier | Per dehumidifier | £600 | £900 | £750 |
Mould removal | Per job | £850 | £2,500 | £1,675 |
Our costs are ballpark averages – get a local tradesperson to quote now
Depending on the extent of damage, your crawl space cleaning and repair costs will be in the region of £1,100 – £11,000.
You might have to pay the higher cost if you have mould damage, foundation subsidence or other issues. This cost, however, would generally cover both repair and cleaning.
To prevent further damage, you may need to look at waterproofing in addition to crawl space repair and cleaning costs.
Crawl space waterproofing cost
Moisture from your crawl space can rise through the floors and cause water damage, rot, mould, and more. To prevent that, you may need to seal it.
Crawl space waterproofing cost falls around £1,200 – £12,000, depending on how big the space is to waterproof.
You can get a vapour barrier that a professional waterproofing contractor would be able to install for you.
The barrier is a plastic sheet that acts as a shield between the crawl space and the floor. Based on how thick you want it to be, this method of crawl space waterproofing costs you between £1,200 – £2,400. A 20mm thick sheet, for example, is 40p – 60p per square foot.

Cost to replace floor joist in crawl space
If your crawl space has been accumulating water damage, the supporting structure might also need some repair. The cost to replace your floor joist in a crawl space is around £75 – £220 per joist.
If, however, the joists are insulated or covered, that could increase the cost to £725 or higher.
The average cost of replacing all floor joists is around £400.
Crawl space encapsulating cost
Crawl space encapsulation is a little more involved than plain waterproofing. This process starts with cleaning the space, sealing and dehumidifying it. As a result, even if the space does get wet, the damp doesn’t linger, and your home stays dry and damp-free.
Whilst encapsulating might use the same vapour barrier, it is sealed tighter over a cleaned, dried, and levelled surface. In some cases, you may even want to use expanding foam for insulation along with waterproofing.
Crawl space encapsulating costs can range from £1,200 – £12,000, averaging around £6,600. The price will vary according to the size of the crawl space and if it needs much cleaning or repairs.
You may also need to install dehumidifiers to keep the air relatively moisture-free. These can cost between £600 – £900 each.
Cost to remove mould from your crawl space
The cost to remove mould from your crawl space is about £850 – £2,500. However, if you have mould, you may also have to deal with water damage too.
FAQs
Why do I need crawl space waterproofing?
Since your crawl space is a cold and dark space with not much ventilation, it is more likely to hold on to moisture. Eventually, this moisture starts seeping into your floor, causing mould and damaging flooring.
As you know, mould and mildew can be bad for your health. By waterproofing your crawl space, you can significantly reduce this problem.
Why do I need crawl space insulation?
As we mentioned earlier, a crawl space is not a warm and dry place. And, as hot air rises, your house starts ‘inhaling’ the cold air from your crawl space and sending it to the upper levels. As a result, your home needs more power to stay warm at a consistent temperature. By insulating your crawl space, you are able to make your home more heat efficient.
Will crawl space waterproofing reduce the amount of water collecting under my house?
Whilst waterproofing will not reduce the water collecting in your crawl space, it will prevent the water from seeping into the concrete. If you do have large amounts of water collecting in this space, you may want to look into drainage solutions.
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